1. Field of the Invention
The invention relates to an earthmoving machine comprising two main subsystems: first means for moving it and second means for moving a mobile part of it. The invention is more particularly concerned with an improvement providing a specific way of synchronizing said first and second means. The invention finds a specific application in machines for compacting the soil where a vibrating system is carried by the machine which moves to and fro along a specific route. In this non-limiting example the invention makes it possible to avoid the generation of vibrations when the machine is stationary likely to result in localized excessive compacting.
2. Description of the Prior Art
A vibrating compactor is a rolling machine that has to execute a particular number of to and fro movements over the soil to be compacted at a predetermined speed chosen to suit the nature of the soil and using vibration means mounted on the machine. To maintain homogeneous compacting and a regular appearance of the surface treated, it is important to start and stop the machine under specific conditions. Starting and stopping have to be gradual to avoid excessive loads on one or other of the two axles of the machine due to the driving torque. As already mentioned, it is also very important to avoid vibrations when stationary. To this end the vibration has to be initiated after the machine has actually moved off and stopped before the machine actually comes to rest.
The conventional way to control movement of the machine uses a swinging lever with a central neutral point to select both the direction of displacement of the machine and the speed at which this occurs. As already mentioned, the machine moves at a speed chosen to suit the nature of the soil. Thus the operator has to move the lever gradually to a position in one direction or the other corresponding to the chosen speed. Also, the vibration means are actuated by a control member situated in the vicinity of the path of movement of the lever so as to be engaged by the lever as soon as the operator commands starting of the machine. The control member is placed in the immediate vicinity of the neutral point of the lever so that the vibration means can function at low displacement speeds of the machine. This results in the risk of compacting when stationary if the operator is not totally familar with the controls of the machine.
The objective of the invention is to facilitate starting and stopping the machine irrespective of the maximum speed chosen and to eliminate the risk of vibration when stationary or moving at very low speeds, by moving the control member for the vibration means to a significant distance from the neutral point of the aforementioned lever. This two-fold advantage is achieved in accordance with the invention by providing the facility to preselect the maximum speed of displacement of the machine and to establish a correspondence between this maximum speed and the maximum travel of the aforementioned lever.